Pterygium inversum unguis

• pterygium inversum unguis - this condition is similar to the pterygium of the proximal nail fold as seen in lichen planus
  • occurs when the volar skin near the hyponychium adheres to the nail plate - this eliminates the distal nail groove and progresses proximally to the nail bed
  • pterygium inversum unguis occurs as a congenital form and an acquired form
  • acquired form is seen most commonly with systemic connective tissue diseases
    • especially seen in progressive systemic sclerosis and systemic lupus erythematosus
  • involvement may be with the entire nail or just a portion
    • one or more nail units may be involved
    • skin in the distal nail unit becomes atrophic
      • changes are secondary to vascular flow occlusion which creates distal hypoxaemia

Reference:

1. Zaiac MN, Daniel CR. Nails in systemic disease Dermatologic Therapy 2002;15 (2); 99–106.